Comment 93 for bug 477226

Post number 60 has the best solution.
You have to ad ppa:ubuntu-audio-dev/ppa to your source list, and update.
After that, install linux-alsa-driver-modules for your kernel version.
If you don't know vhat kernel version you have type uname -a in Terminal.
The second solution that also works fine is adding options snd-hda-intel model="olpc-xo-1_5" at the end of /etc/modprobe.d/alsa-base.conf. But, when I record sound with that option I get some background noise that I can't get rid of. Maybe that is just my configuration because on PC Linux OS adding that line in alsa-base.conf works just fine.
I tried those two solution and I can confirm that they both work. I recomend first solution.